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Mark wrote Oct 28 in response to Steve's battery charging question:
> > The aux battery relay closes whenever the alternator is producing
voltage
> (i.e. when the engine is running). When the relay closes, the aux battery
> and the main battery are both connected to the regulated output of the
> alternator.

I agree with what Mark said. But I just want to put in my two cents.
I think the best way to keep 2 batteries separated, but charged, is to
install an automatic battery isolator. It makes a much cleaner
installation.
If installed properly, it will prevent the main battery from discharging
when you use the camping equipment. The device is totally maintenance-
free and reliable.
I've been using isolators in my vanagons for more than 12 years.
If anyone is interested in a multi-battery isolator for a vanagon
(alias Bosch alternator), call Sure Power Industries, Inc.
                                          Tualatin, Oregon 97062
                                          phone (503) 692-5360
                                          fax (503) 692-9091
If you have the big 90 amp alternator on the later vanagons,
only use model number 1202R, maximum 120 amp.
On the air-cooled vanagon smaller alternators, you can use
model number 952R, maximum 95 amp.
My 1990 vanagon burned out the 952R, so I had to replace it
with the stronger 1202R.
The main difficulty with this installation is that it requires a
a separate cable from the engine compartment to the
auxillary battery, and a minor alteration to the regulator.
Anyone else using this isolator?
Harald
'90 westy